Crossover Shipgirls: Building a Dimensional Empire from Scratch

Shua—

The Astral Express cut through the sea of stars, heading toward the planet ahead.

This was the first time the crew had arrived in another world, and everyone was brimming with excitement.

”Mm, I can’t sense any fluctuations of Imaginary energy here. Aeons can’t interfere on this side.”

Herta tilted her head up, observing.

She could still use her own Imaginary energy, but somewhere beyond perception, her connection to higher-dimensional existences had been severed.

Although different worlds within the Star Rail universe were isolated from one another, they still existed under the gaze of Aeons. This place, however, was like a lawless zone.

Completely detached from the Tree and Sea system.

Of course, there was still a faint trace of Imaginary energy—emanating from Setsuna himself, the power of Trailblaze.

”Commander, where is this place?”

Gudako, Stelle, Himeko, and the others gathered around him.

Shua—

The higher-dimensional star map was still shrouded in fog.

”No idea. We might have to make contact with this world’s civilization before it reveals itself.”

Setsuna shrugged.

Unlike the civilizations he personally scouted on the star map, the worlds reached by the Astral Express through trailblazing were essentially random. There was no way to know in advance where they would arrive.

When placing the beacon, he could only roughly determine that the overall level of this region wasn’t particularly high—there wouldn’t be anything on the level of Tengen Toppa.

”Uh, that does fit the definition of trailblazing, doesn’t it?”

Himeko thought about it and found the idea of discovering and exploring unknown worlds quite interesting.

In the future, they could roam freely across the multiverse aboard the Astral Express, actively charting territory for the Starsea Empire.

Humm...

A Sophon instantly scanned a region spanning thousands of light-years.

”No space-age civilizations detected within this world. No interstellar vessel trajectories observed. Intelligent life confirmed within the target star system.”

”Scanning... confirmed. Technological level approximately medieval. Presence of 553 magic-based technologies.”

The surrounding stellar structure differed from the solar system and any world they had previously encountered.

”Huh? Medieval? A magical civilization?”

Herta and March 7th found it novel.

After breaking through the atmosphere, the Astral Express entered a cruising state above the planet.

Looking down, it revealed a classic pastoral scene.

Endless grasslands and forests, farmers working in wheat fields, travelers hurrying along in horse-drawn carriages...

Most villages were scattered across the continent like stars. In certain regions, large human cities could be seen.

Towering walls, clustered palaces, guards patrolling the streets... no different from medieval cities in most fantasy works.

In areas far from human settlements, lurking in the shadows, restless monsters could also be spotted.

”Cold weapons and magic—a classic combination. I’ve seen it countless times in novels.”

Herta nodded.

At the same time, the moment the planet was scanned—

The name of this world appeared on Setsuna’s higher-dimensional star map.

[New World Discovered]

[Frieren: Beyond Journey’s End (Tier-II Magic Age)]

This world widely utilizes magic, but its overall level is not high.

In addition to humans, there exist elves, monsters, and other magical beings.

[Comparison of Strengths:]

- Military Strength: Like an Ant.

- Technological Level: Like an Ant.

- Economic Power: Like an Ant.

”???”

”Huh?”

Setsuna froze for a moment.

”Well, would you look at that—we ended up here?”

He was quite familiar with this world, and its difficulty wasn’t high.

It was roughly the story of an elven mage who, after defeating the Demon King, set out on another journey to understand humans.

As a sword-and-magic world, it didn’t have absurd monsters everywhere, nor did it have unreliable gods like Aqua.

Everything was normal—textbook-level normal for a medieval fantasy setting.

”Hm?”

The crew didn’t quite understand, but leaned in curiously.

”Tier-II magic world? Is that your classification system?”

Herta asked.

”More or less. That’s how the star map labels it.”

Setsuna replied.

”The classification is pretty broad. Generally speaking, the higher the level, the stronger and larger the world’s overall scale. Right now, the highest is Tier-V.”

”A Tier-II world... its magic is still far from reaching the level of plucking stars or reshaping the structure of the universe.”

”Oh...”

Herta nodded thoughtfully.

”So our main objective is to conquer this world, bring it under the Starsea Empire’s control, and capture a few girls to offer to the Commander.”

Gudako clenched her fist and pulled out a few scrolls.

”??”

”Wait, why does that sound so weird?! You’re making the Sacrosanct sound like some Demon King who kidnaps children from villages!”

March 7th was stunned.

”Aren’t we here to explore new worlds?”

”Uh, maybe the wording is a bit off, but the tasks are basically the same.”

Gudako scratched her head.

”Isn’t there a Demon King in this world? Following tradition, we defeat the Demon King first, then take control of the entire planet and incorporate it into the Starsea Empire’s territory.”

”Along the way, we recruit anyone qualified to join the Starsea Empire. How about it? Simple mission, right?”

”Expanding territory and expanding the harem are both forms of trailblazing!!”

”???”

March 7th and Himeko were left dumbfounded, utterly shaken.

It made so much sense they couldn’t even refute it.

”Mm, works for me.”

Setsuna glanced at the world below.

”The difficulty here isn’t high. Let’s finish it quickly.”

”Hmm... maybe we can add a few new members to the magic academy later?”

Crack—

Gudako piloted the Strelizia, leaping down with Stelle.

”Woohoo—”

Landing in another world for the first time filled the Stellaron with excitement.

”Let me handle this one!!! Demon King—where are you?!”

...

In the northern lands, at the edge far from human villages, within a vast forest.

As night gradually fell, the surroundings grew quiet, leaving only faint bird calls and the rustling of animals.

A blue-haired boy dressed in coarse cloth hurried through the forest, carrying a bamboo basket.

He had only intended to gather some herbs, but unfortunately lost his way.

As darkness deepened, the scenery around him became increasingly unfamiliar. He had wandered into the depths of the great forest.

”Ugh...”

After running around like a headless fly for a while, Himmel finally sat down beside a large tree, lowering his head and hugging himself.

He had no idea where he was, nor how far he was from any human village. Fear engulfed the young child.

Sha, sha—

After an unknown amount of time, footsteps sounded ahead.

A girl with silver twin-tails and pointed ears walked over.

She wore a simple plain-colored short robe with a cloak draped over it, carrying a basket of herbs as well.

Her face was cute, yet completely expressionless.

”Elf!”

Himmel was startled.

In this world, there were not only humans, but also long-lived elves, strong dwarves, cunning demons, and undead controlled by magic.

”Are you lost?”

Frieren glanced down at Himmel sitting on the ground and pointed in a direction.

”That way... there’s a human village.”

Her tone was indifferent, with not a single extra word.

”Ugh...”

Himmel found her somewhat cold and became uneasy.

”...”

Frieren frowned slightly, noticing his fear.

Perhaps wanting to comfort this human child and make him less afraid, she raised her staff and prepared to cast a spell.

Whoosh—

A flash of white light burst forth as magic scattered.

A small field of colorful flowers appeared before them.

Petals danced through the air, and a gentle fragrance drifted over.

This was a spell she had learned nearly a thousand years ago while studying under her master, Flamme.

”Whoa...”

Just as he was staring in a daze—

”Hah!!!—”

”Found it! Perfect timing, right here!!!”

Shua!!—Crack!

From the top of the forest came the sharp sound of something tearing through the air, followed by the cracking of breaking branches.

Boom!!

A red-and-white meteor descended from the sky, landing right in front of the two.

Dust scattered across the ground, and the heavy impact startled flocks of birds into flight, chirping wildly as they fled.

”Cough, cough—”

Both of them choked slightly. When they looked up again—

A towering mecha stood upon the earth, far taller than the tallest trees in the forest. To mortals, even reaching its ankle would be impossible.

Its metallic exterior, smooth and elegant lines, and massive frame—this ultimate industrial aesthetic was captivating even in another world.

Sitting on the shoulder of the Strelizia was a gray-haired girl in a black jacket, resting a baseball bat on her shoulder.

”Yo? Looks like we showed up just in time?”

Stelle let out a whistle.

”Holy—!!!”

Young Himmel was completely dumbfounded.

”D-Did that elf just turn into a giant mecha?!”

”What kind of magic is that?! That’s insane!!!”

”???”

Even the usually expressionless Frieren was stunned.

She stared at the Strelizia, sizing it up for quite a while.

”Yo.”

Stelle jumped down from the mecha and glanced at Himmel.

The synchronized image was also transmitted back to the Astral Express.

Hmm, this timeline was quite subtle.

At this point, the hero’s party was likely still in their childhood phase—Himmel was still a kid.

—Except for Frieren.

Despite her youthful appearance, she was actually an old veteran who had trained for over a thousand years.

”We’re from the Starsea Empire. Nice to meet you.”

Stelle greeted the two before looking at Himmel again.

”It’s dangerous for a kid to stay alone in the forest at night. Hurry home.”

”Uh...”

Himmel couldn’t stop glancing at the Strelizia.

Perhaps it was instinct—every boy would be drawn to such a cool and domineering mechanical construct.

”Big sis, this is...”

He stammered.

Showing off in front of a native felt incredibly satisfying to the gray-haired girl.

They held no ill intent toward Himmel. Among heroes across different worlds, he was considered one of the more upright ones.

However, once the Starsea Empire arrived here, the entire world’s situation was bound to be overturned.

”Be good, head home early.”

Stelle pointed him in a direction as well.

Seeing how reluctant he was to look away from the Strelizia, she pulled out a small mecha toy from her pocket and tossed it to him.

”Here, take it home and play with it.”

”Wah!!—”

A medieval child had never seen such an advanced item before. Himmel clutched the toy, unwilling to let go, bowing repeatedly before running off in a hurry.

”?”

Frieren stared at the two with slight confusion.

From them, she couldn’t sense any demonic aura—they were genuine humans.

But humans piloting a giant mecha in the medieval era... that was far too advanced.

”Who... are you?”

”Simply put, we’re a civilization from another world.”

”Mm... due to some unexpected circumstances, we arrived here, so we thought we’d take care of things along the way.”

The gray-haired girl replied.

”For example, conquering this world—defeating the Demon King, the monsters, and even the kings and nobles, then making them pay tribute to us or something.”

Perhaps influenced by Gudako, she had completely accepted the Starsea Empire’s methods.

Their ways of thinking were perfectly in sync.

”???”

Frieren was even more confused.

”Want to join us? We’ll go defeat the Demon King... and conquer the world.”

Stelle got straight to the point.

”...”

After a moment of thought, Frieren shook her head, gripping her staff as she took two cautious steps back.

”No.”

These extraterrestrial visitors felt strange no matter how she looked at them—especially the one carrying a baseball bat. She didn’t seem trustworthy.

”Huh?”

Stelle was shocked.

”What do we do if she refuses?”

”Should we knock her out and bring her back to the Commander?”

”...”

Setsuna couldn’t help but sigh at these two troublemakers.

”Didn’t Fujimaru Ritsuka teach you how to communicate properly when carrying out recruitment missions?”

Shua—

His projection appeared before Frieren.

”Greetings. I’m the Commander of the Starsea Empire. We arrived here by accident while exploring new worlds.”

”We won’t be staying long and will return soon. I’m quite interested in you—if you have time, feel free to come aboard and have a chat.”

He paused briefly.

”In terms of magic, you should have common ground with our Magic Department. Also, I can do you a small favor.”

”Would you like to see Flamme again?”

”!?”

Frieren froze.

The great mage Flamme was her master from over a thousand years ago, and one of the most important figures in her life.

When her elven village was slaughtered by demons in her childhood, she had met Flamme by chance and followed her ever since, traveling and learning magic together.

Unfortunately, as a human, Flamme’s lifespan couldn’t compare to that of an elf. After accompanying her for over fifty years, she passed away.

She had never told anyone about this, and a stranger from another world shouldn’t have known events from over a thousand years ago.

”You know about her? That was over a thousand years ago.”

”Time holds no meaning before me. Even fifty thousand years ago—I could take you back there.”

Setsuna smiled.

”Don’t you want to go back and let Flamme see the you of today?”

”!!!”

Frieren frowned and stepped back again.

She felt as if she had been struck directly—what she heard sounded like myth.

Among all the magic she knew, she had never heard of time-reversing magic.

Flamme had never taught her such a thing, and Frieren doubted even her master’s master—the ’Living Grimoire,’ Serie—could wield such power.

”You... can really do that?”

The elven mage’s voice trembled slightly.

”Of course. Come aboard and see for yourself.”

...

Ten minutes later.

The silver-haired twin-tailed elven mage boarded the Astral Express and stood before Setsuna.

”You’re the first guest from another world!”

Pom-Pom, along with Herta and Ruan Mei, found it incredibly fascinating.

To them, Frieren was a true ’otherworlder.’

Completely detached from the Imaginary energy system, originating from a world with entirely different rules.

Especially after learning about concepts like magic, Demon Kings, and heroes, the two geniuses were even more intrigued, feeling that staying by Setsuna’s side truly broadened their horizons.

”Yo, nice to meet you.”

Setsuna casually rubbed Frieren’s head.

Age was just age—within the Starsea Empire, there were plenty who had lived for thousands or even tens of thousands of years, not to mention beings like Nyarlathotep whose age would break any counter.

This ’old mage’ could only be considered a young person in the Starsea Empire—Herta had probably lived longer than her.

—Though both of them were equally flat.

”Mm...”

Everything aboard the Astral Express was completely unfamiliar and novel to Frieren.

The space-age decor was far too advanced, far too modern. There were many devices she didn’t even know the purpose of.

The people before her were equally unfamiliar—completely different from the mages and nobles she had known.

”...Where are you from?”

She asked, her tone calm and emotionless.

”Another world. A universe beyond this one.”

Setsuna replied concisely.

”Uni... verse?”

Such a high-level concept was beyond Frieren’s understanding. Setsuna simply handed her a tablet.

”Here, stay here for a bit. If you have time, take a look yourself.”

”...”

”You really can use time-space magic?”

Frieren stared at Setsuna as she asked. She couldn’t sense any trace of magic from him.

Either her perception of mana was flawed, or he had concealed himself so perfectly that he appeared no different from an ordinary person.

All she could vaguely feel was that this man was anything but simple.

”Magic... strictly speaking, that’s not quite accurate. But traveling through time isn’t difficult for us.”

Setsuna smiled.

”Once we’re done with matters here, we’ll go bring your teacher back.”

He glanced around. There wasn’t much to do in Frieren’s world.

Just bring back a few girls, defeat the Demon King, and take control of the entire world.

”Himeko, March 7th—you can observe how the Starsea Empire handles standard expansion procedures.”

”It’ll serve as a reference for when you pilot the Astral Express to explore other worlds in the future.”

”Oh!”

The two quickly agreed. March 7th even pulled out a notebook, ready to study seriously.

”First, the initial step is to determine the personnel we want to recruit from this world.”

Stelle listed out a roster on the holographic interface.

From Frieren’s master’s master, Serie, to one of the Seven Sages of Destruction among the demons, Aura—everyone was included.

”Next, we deal with the natives and establish a unified regime under the Starsea Empire. The Sophon will handle administrative affairs in each world.”

Clank—

One of the Astral Express’ armed carriages opened, and thousands of Angeloids surged out, descending toward the surface.

This kind of task was second nature to them. Medieval natives would practically drop to their knees upon seeing those white-winged angels.

”Ah?!”

In the northern lands, a king who had been sitting in his palace looked up—only to find hundreds of fully armed angels surrounding it, trembling in fear.

”You... intend to conquer the entire world?”

Frieren was somewhat stunned.

She wondered if she should do something—but had no idea what she could even do.

She had long lived in seclusion, rarely interacting with human society, and had no interest in conflicts between kingdoms.

”Of course. Since we’re already here, it’s just a side task.”

Stelle gave a matter-of-fact answer.

”What about the demons and the Demon King?”

Frieren asked.

Back then, Flamme had instructed her to act cautiously, conceal her strength, and wait until the time came to defeat the Demon King.

Many hero parties had attempted to defeat the Demon King, but none had ever succeeded.

”That part is even simpler.”

The nanomachines yawned.

”Kiana, March 7th, Bronya... you guys go take care of the Demon King and bring Aura back while you’re at it.”

”Oh—should I call Kafka over too? She could teach Aura how to play the violin.”

”Time limit: two hours. If you go over, the Commander will spank you when you get back.”

”Hm?”

”Wait, there’s a reward like that?!”

—

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